• Journal of Institute of Control, Robotics and Systems
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• v.5 no.7
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• pp.808-813
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• 1999

A fuzzy learning method to control an unstable and multivariable system is presented in this paper, Because the multivariable system has generally a coupling effect between the inputs and outputs, it is difficult to find its modeling equation or parameters. If the system is unstable, initial condition rules are needed to make it stable because learning is nearly impossible. Therefore, this learning method uses the initial rules and introduces a cost function composed of the actual error and error-rate of each output without the modeling equation. To minimize the cost function, we experimentally got the Jacobian matrix in the operating point of the system. From the Jacobian matrix, we can find the direction of the convergence in the learning, and the optimal control rules are finally acquired when the fuzzy rules are updated by changing the portion of the errors and error rates.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.8
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• pp.24-33
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• 1999

This paper investigate the effects of the variations of engine operation condition in the flame kernel formation and developmnet . A model for calculating the initial kernel development in spark ignition engines is formualted. It considered input of electrical energy, combustion energy release and heat transfer to the spark plyg, cylinder head, and unburned mixture. The model also takes into accounts strain rate of initial kernel and residual gas fraction. The breakdown process and the subsequent electrical power input initially control the kernel growth while intermediate growth is mainly dominated by diffusion or conduction. Then, the flame propagates by the chemical energy and turbulent flame expansion. Flame kernel development also influenced by engine operating conditions, for example, EGR rate, air-fuel ration and intake manifold pressure.

• Proceedings of the Membrane Society of Korea Conference
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• 1999.07a
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• pp.95-96
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• 1999

The ultrafiltration behavior of dilute colloidal solution containing Si particles has been investigated. The experiments in cross flow mode have been performed at different operating condition by using the membrane with 20 kDa cut-off. The flux decline was due to the development of membrane fouling which was a dynamic process of two distinctive stages. For the high trans-membrane pressure, the pore blocking resistance was dominant at the initial period of filtraion and was followed by the cake resistance. And for the low cross flow velocity, the membrane fouling was governed by the cake filtration model at the initial stage of filtration process. Flux jump was observed temporally during the membrane filtration of mixed feed solution.

• Journal of Environmental Science International
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• v.11 no.6
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• pp.577-582
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• 2002

Selective catalytic reduction and selective non-catalytic reduction processes are mainly used to treat nitrogen oxidants generated from fossil-fuel combustion. Especially, the selective non-catalytic reduction process can be operated more economical and designed more simply than the selective catalytic reduction. For this reason, many researchers carried out to increase the removal efficiency of nitrogen oxidants in the condition of low oxygen concentration by using the selective non-catalytic reduction process. However, this study was flue gas contained high oxygen concentration of 20(v/v%) with ammonia as a reducing agent. Moreover, it carried out experiment with many factors that are reaction temperature, retention time, initial NO concentration, NSR(normalized stoichiometric ratio). It was determined optimal operating conditions to improve NO removal efficiency with SNCR process. The De-NOx efficiency was increased with NSR, initial NO concentration and retention time increasement. This study has NO removal efficiency over 80% in the high oxygen concentration as well as low oxygen concentration. The injection of reducing agent may be considered for SNCR process and facility operation in 850$\^{C}$ of optimal condition.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.720-724
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• 2008

The purpose of this study is to evaluate the PM10 removal efficiencies of an Air-washer and an Ultrasonic humidifier by mock-up experiments. The concentrations of PM10 were measured at 5 minute intervals using $\beta$-Ray method. The average PM10 removal efficiency of the Air-washer was 79.8%, while the PM10 concentrations increased with the operation of Ultrasonic humidifier. In the case of operating the Air-washer, the R.H(Relative Humidity) level of the test room was maintained at around 45%, regardless of initial R.H condition. The R.H of the test room with Ultrasonic humidifier was influenced by the initial R.H condition.

• Journal of the Korea Organic Resources Recycling Association
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• v.20 no.4
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• pp.106-117
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• 2012

Indirected heating dryer is used as one of the food waste treatment technologies for the production of the drier material supplied to the recycling facilities or end user. This study investigated the effect on drying efficiency for the operation of rotating screw with the circulating and falling movements on indirected drying process of food waste. The screw operating condition showed higher drying efficiency despite of the shorter drying time compared to the screw non-operating condition. The moisture content decreased to 14.4% from the initial moisture content of 77.1% after drying 5 hours in the screw operating condition. On the other hand, in the screw non-operating condition, the moisture content decreased slightly to 35.6% after drying 16 hours. During the drying process, variations of the water evaporation rate and particle size showed different tendencies depending on the moisture content regions. In the higher moisture content region above the glue zone(moisture content of about 50%-60%), the particle size increased and the water evaporation rate reached the highest peak. In the range of glue zone, the particle size maximized while the water evaporation rate decreased sharply. In the lower moisture content region below the glue zone, the water evaporation rate and particle size both decreased at the same time. The particle size distribution was widely ranged from 25.0mm to 0.25mm in the screw operating condition while it was narrowly distributed in the screw non-operating condition from 25.0mm to 3.56mm, especially highly concentrated to 25.0mm. It was regarded that the hygroscopic, capillary and gravitational water evaporated more easily from the intra-particle during the circulating and falling movement caused by the rotating of the screw and the difference of the cohesional force of water within intra-particle depending on the moisture content regions. Comparing the effect of the circulating and falling movement on drying efficiency, the water evaporation rates per time and per weight of dry solid in the screw operating condition were higher about 364% and 356%, respectively, than those of the screw non-operating condition.

• International Journal of Railway
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• v.5 no.1
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• pp.1-9
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• 2012

Reliability means that a product maintains its initial quality and performance at a certain period of time (time, distance, cycle etc) under given condition without failure. The given conditions include both environmental condition and operating condition. Environmental condition means a common natural environment such as temperature, humidity, vibration, and working condition means an artificial environment such as voltage, current load, place for installment, and hours of use, which occurs during the life of the product. In the field of railway vehicles, it is mandatory to use a part with the proved reliability as the extension of the life of vehicle become highly necessary. But the reliable assessment method for the reliability of the part is insufficient. If the reliability of the railway vehicle parts could be assessed by using the field data, the reliability of the entire system could also be evaluated reliably. In this study, life span of micro-switch for master controller is analyzed and prediction is performed based on its field data given by an operator considering the special circumstances of railway vehicles such as the operation of a large number of trains on the same line.

• KSBB Journal
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• v.22 no.4
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• pp.244-248
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• 2007

The treatment of a model wastewater containing high concentration, 10 $g/{\ell}$, of phenol in an integrated wet oxidation-aerobic biological treatment was investigated. Partial wet oxidation under mild operating conditions was capable of converting the original phenol to biodegradable organic acids such as maleic acid, formic acid and acetic acid, the solution of which was subjected to the subsequent aerobic biological treatment. The wet oxidation was carried out at 150$^{\circ}C$ and 200$^{\circ}C$ and the initial pH of 1 to 12. The high temperature of 200$^{\circ}C$ and the acidic initial condition in the wet oxidation led to effluents of which biodegradability was higher in the subsequent biological oxidation process, as assessed by chemical oxygen demand (COD) removal. Homogeneous catalyst of $CuSO_4$ was also used for increasing the oxidation rate in the wet oxidation at 150$^{\circ}C$ and initial pH of 3.0. However, the pretreatment with the catalytic wet oxidation resulted in effluents which were less biodegradable in the aerobic biological process compared to those out of the non-catalytic wet oxidation at the same operating conditions.

• Elastomers and Composites
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• v.52 no.4
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• pp.237-241
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• 2017

The tensile strength (TS) and elongation-at-break (EB) loss of a CR/CB rubber composite sample prepared for the automotive parts were measured after accelerated thermal ageing at temperatures of 100, 120, 140, and $150^{\circ}C$. The change in TS was observed to be linear from the master curve prepared using the time-temperature superposition-principle (TTSP). An Arrhenius type of shift factor, $a_T$ was used to predict the life time of the sample, and a plot of ln $a_T$ vs. 1/T was also shown to be linear. The activation energy ($E_a$) of the sample was calculated as 70.30 kJ/mole from the Arrhenius plot. The expected life time of the sample was predicted at the given operating conditions by applying Arrhenius analysis. Assuming the $E_a$ value was constant at lower operating condition, life time of the sample was calculated as 2.3 years when the life limit was set as time to reach the 20% decrease of the initial TS value at operating temperature of $40^{\circ}C$.

• Transactions of the Korean hydrogen and new energy society
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• v.20 no.3
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• pp.256-263
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• 2009

The operating range of HCCI engine is narrow due to excessive rate of pressure rise on high load. The fuel stratification is proposed to solve the problem. The purpose of this study is to gain a better understanding of the effects of fuel stratification on reducing the pressure-rise rate at high load in HCCI combustion and to investigate that the operating range is expanded for fuel stratification in the preceding condition of initial temperature and equivalence ratios. The engine is fueled with Di-Methyl Ether (DME) which has unique 2-stage heat release. The computations were conducted using SENKIN application of the CHEMKINll kinetics rate code. Calculation result shows that proper fuel stratification prolongs combustion duration and reduce pressure rise rate.